1. Field of the Invention
The present invention relates to a magnetoresistive head, a method of manufacturing the same, and an apparatus for manufacturing the same and, more particularly, a method of manufacturing a magnetoresistive head including a shaping step that includes polishing the magnetoresistive head, a magnetoresistive head obtained by the method, and an apparatus for manufacturing the magnetoresistive head.
2. Description of the Prior Art
A reproduction magnetic head for a high density magnetic disk apparatus has a magnetoresistive device in which electric resistance is varied according to intensity of a magnetic field. As a magnetoresistive head (referred to as a "MR head" hereinafter), there are AMR (anisotropic magnetoresistive) heads that use an anisotropic magnetoresistive effect, spin valve heads that use a spin valve effect, and the like.
In the MR head, change in resistance may be detected as change in voltage by supplying a constant current to a sense area for a signal magnetic field. It is not preferable that the sense area has too small resistance value since change in resistance caused by the signal magnetic field becomes small.
For this reason, the resistance value of the MR head has been adjusted appropriately. As one method of adjusting such resistance value, there is a method of polishing a top end of a pattern that is part of the MR head. In this case, the MR head which is formed on a rod-like block cut out from a wafer is polished.
As methods of optimizing a polishing amount of the MR head, two following methods have been adopted. These two methods are similar in that the rod-like block and the MR head are polished simultaneously with abutting the top end of the MR head formed on the rod-like block to an abrasive cloth, but different in a process of monitoring--therefor; a polishing amount.
In the first method, as shown in FIG. 1, on a rod-like block 101 polished with an abrasive cloth 100, a polishing amount is measured by observing optically a height of monitoring patterns 103 which are arranged on the both sides of the MR head 102 by a microscope or the like.
However, since the monitoring patterns 103 to be measured optically, as well as the MR head 102, are covered with a protection film (not shown), sometimes dual images of the monitoring patterns 103 are observed because of optical irregular reflection by the protection film. This causes reduction in measuring precision.
In the second method, as shown in FIG. 2A, on the rod-like block 101 polished with the abrasive cloth 100, monitoring wirings 105 are first connected to conductive monitoring patterns 104 which are arranged on the both sides of the MR head 102, and resistance values of the monitoring patterns 104 are then measured by supplying electric current to the monitoring patterns 104.
Measurement of change in the resistance value by polishing operation may be carried out with respect to the MR head 102. A relationship between polishing dimension of the MR head 102 and the resistance value RF and a relationship between polishing dimension of the monitoring patterns 104 and the resistance value RF have been given as curves A and B in FIG. 2B, for example. Therefore, polishing dimension may be calculated based on the resistance value. In other words, in principle, a desired dimension has been polished when a predetermined resistance value has been detected.
However, since there exist variation of contact resistance and error of every manufacturing step in the monitoring patterns 104 and the MR head 102, respective rod-like blocks 101 are likely to exhibit uneven characteristic curves A and B in FIG. 2B even if the monitoring patterns 103 and the MR head 102 are formed to have the same structure. If the characteristic curves deviate from each other, different polishing dimensions are caused even if the same resistance value has obtained after polishing, which results in uneven characteristics of the devices.
Furthermore, in the above two polishing method, there is a disadvantage that much time and labor are required for polishing operation since the polishing is interrupted to monitor polishing states.